How common is infidelity in Britain? What the surveys really show

That last figure is the odd one out in forty years of British opinion polling. In 1983, the first British Social Attitudes survey found that 42% of adults saw nothing wrong at all in sex before marriage; by 2022 the figure was 78% ^[1]. Over the same period, the share saying it is always wrong for a married person to have sex with someone other than their partner moved from 58% to 57%, a proportion the report's author, Elizabeth Clery, said had "remained remarkably stable" ^[1].

How many Britons say they have cheated?

Between a fifth and a quarter of British adults tell pollsters they have been unfaithful at some point, and the share has been fairly steady across three YouGov surveys since 2010. The most recent, carried out on 9 and 10 July 2026 among 1,882 adults and published on 17 August 2026, found that 23% of those who had ever been in a relationship said they had cheated on a partner ^[2][3]. Asked to be more specific, 17% said they had been sexually unfaithful, 18% emotionally, and 12% both ^[3].

Two earlier YouGov polls, both linked to The Sun, gave similar orders of magnitude. A YouGov Labs poll reported in March 2010, which the newspaper's interest in a footballer's affair had prompted, found that 19% of respondents had cheated on a partner, with men slightly more likely than women to say so ^[4]. The poll also asked about the footballer John Terry, whose affair had cost him the England captaincy: 51% of men and women called his cheating unforgivable, and 56% thought cheating on a spouse with another woman was worse than paying for sex, against 22% who thought the reverse ^[4]. In May 2015, another poll for the same newspaper found that 20% of British adults said they had had an affair, and about a third said they had thought about it ^[5].

The three surveys did not ask exactly the same thing. The 2026 question was put to people who had been in any relationship and allowed emotional cheating to count ^[3], while the 2015 survey asked about "an affair" ^[5]. Neither publication gives the full question wording in the article itself, and the 2010 and 2015 articles do not state their sample sizes or fieldwork dates ^[4][5]. They are best read as consistent snapshots, without treating the small changes between them as a trend.

For comparison, a YouGov survey of about 1,000 Americans in May 2015 found 21% of men and 19% of women admitting to cheating, with about 7% declining to answer, a reminder that a share of respondents in any such poll chooses not to say ^[6]. American attitudes and the legal side of the question in the United States are covered in a separate article on adultery laws by state.

What the main British surveys say about infidelity

Survey	When	Sample	What it measures	Headline result
YouGov big survey on relationships	9-10 July 2026	1,882 adults	Ever cheated, among people who have had a relationship	23% (17% sexually, 18% emotionally)
YouGov for The Sun	May 2015	Not stated	Ever had an affair	20% (men 20%, women 19%)
YouGov Labs (prompted by The Sun)	March 2010	Not stated	Ever cheated on a partner	19%
British Social Attitudes	1983 and 2022	National survey	Extramarital sex always wrong	58% then 57%
Natsal-3	2010-12	15,162 aged 16-74	Non-exclusivity in marriage or cohabitation always wrong	Men 57.2%, women 65.0%
Natsal-2	1999-2001	11,161 aged 16-44	Concurrent partnerships in the past year	Men 15%, women 9%
Finding Fault (Nuffield)	Divorces of 2015	England and Wales	Divorces relying on adultery	12% (behaviour 48%)
Natsal-4	2022-24 fieldwork	About 19,000 aged 16-59	Results due end of November 2026	Not yet published

What does Natsal measure, and why does it rarely say "infidelity"?

Natsal, the National Survey of Sexual Attitudes and Lifestyles, does not ask people whether they have cheated. It measures behaviour that can include infidelity, mainly the number of partners and whether partnerships overlapped in time, which researchers call concurrency. Since its second wave it has used a computer-assisted self-interview for the most sensitive questions ^[7], a method described in our guide to the Natsal survey.

The clearest published concurrency figures come from Natsal-2. That wave interviewed 11,161 people aged 16 to 44 between 1999 and 2001, and among those who had a partner in the previous year, 15% of men and 9% of women reported concurrent relationships ^[7]. Concurrency is a wider category than adultery. It covers anyone with two partners whose relationships overlapped, including single people dating two others, and it says nothing about whether either partner knew or agreed. The analysts also warned that some changes between 1990 and 2000 might reflect greater willingness to report, helped by the self-interview format ^[7].

Natsal-3, with 15,162 participants aged 16 to 74 interviewed between 6 September 2010 and 31 August 2012, gives a sense of how many people have more than one partner at all ^[8]. In its reference tables, 67% of men and 68% of women reported exactly one opposite-sex partner in the past year, and 18% of men and 22% of women none ^[9]. Over five years, 55% of men and 60% of women reported a single opposite-sex partner ^[9]. Those with two or more partners in a year are a minority, and only some of them were in a committed relationship at the time, so the tables cannot be turned into an infidelity rate.

Has the British view of adultery changed since the 1980s?

Disapproval of adultery has barely moved since the 1980s, while tolerance of sex before marriage has almost doubled. British Social Attitudes, run by the National Centre for Social Research, asks about "a married person having sexual relations with someone other than his or her partner" ^[1]. In both 1983 and 2022, more than eight in ten people said this was always or mostly wrong, and the "always wrong" share went from 58% to 57% ^[1].

The two attitudes are linked in a lopsided way. Among people who say sex before marriage is always wrong, 99% also say extramarital sex is always wrong; among those who see nothing wrong in sex before marriage, 54% still say an affair is always wrong ^[1]. The longer story of premarital attitudes is told in how British attitudes to sex before marriage have changed.

Religion separates the groups more than sex does. In the 2022 survey, 80% of men and 77% of women saw nothing wrong in sex before marriage, while the figure ranged from 92% among people with no religion to 73% among Church of England adherents, 75% among Roman Catholics, 64% among other Christians and 32% among members of non-Christian religions ^[1]. The report does not give the same breakdown for extramarital sex, so it is not possible to say from BSA alone whether religious Britons are stricter about affairs than others ^[1].

Natsal points the same way and suggests disapproval even grew among younger adults. In Natsal-3, 57.2% of men and 65.0% of women aged 16 to 74 said that sex with someone other than one's partner while married or living together was always wrong ^[8]. Among people aged 16 to 44, the share rose from 51.2% to 62.5% for men and from 59.7% to 69.8% for women between Natsal-2 and Natsal-3 ^[8]. Over the same decade, acceptance of one-night stands fell among men in that age group, from 27.3% to 20.2% saying they were not wrong at all ^[8].

YouGov's 2026 poll found the same firmness. Three quarters (76%) said there was no justification for cheating, while 11% said it could be acceptable in some circumstances, a figure YouGov describes as consistent across social groups ^[3].

Do men and women cheat at the same rate?

Surveys find a small gap between men and women in reported cheating and a larger one in attitudes. In YouGov's 2015 poll, 20% of men and 19% of women said they had had an affair, a statistical tie, but men were more likely to have thought about it (37% against 29%) and to have had more than one affair (49% against 41% of those who had strayed) ^[5]. The same poll asked who the other person was: friends came first (43%), then work colleagues (38%), strangers (18%), former partners (12%), neighbours (8%) and a partner's relatives (3%) ^[5]. More than half of the women who had had an affair named a friend, against about a third of men, while men more often named a colleague, a stranger or a neighbour ^[5]. The 2010 poll also found men slightly ahead, with 8% of men and 5% of women admitting to cheating 20 or more times ^[4].

Natsal's behavioural data show a wider gap. The Natsal-2 concurrency figures were 15% for men and 9% for women ^[7], consistent with the general finding that men report more partners than women, a gap Natsal has found narrowing as women's reported numbers have risen ^[10].

Women are stricter judges. In Natsal-3, women were more likely than men to call non-exclusivity in a marriage or cohabitation always wrong (65.0% against 57.2%), and only 9.3% of women against 17.5% of men saw nothing wrong in one-night stands ^[8]. YouGov's 2026 poll found women more likely than men to describe every listed behaviour as cheating, and the gaps were large on emotional matters: 60% of women and 43% of men called a deep emotional attachment cheating ^[3].

The sexes also differ on which betrayal hurts more. In 2026, 46% of men and 35% of women said a sex-only affair would bother them more, while 29% of women and 20% of men picked an emotional affair ^[3]. Motives differ too, at least in the 2010 poll: 58% of women who had cheated cited an unhappy marriage, against 35% of men, while 21% of men and 4% of women said they did it for a thrill ^[4]. Smaller shares blamed drink (12% of men, 7% of women) or revenge on a partner (10% and 4%), and 8% of each sex said boredom ^[4].

Does age change the picture?

Age shapes what people count as cheating more than whether they say they have done it. YouGov's 2026 survey found that 53% of people over 60 called kissing someone else cheating, against 78% to 86% in younger age groups ^[3]. Under-30s were the most likely to count flirting (45%), having a crush (27%) and fantasising about someone else (27%) as infidelity, and 57% of them said the same about engaging with OnlyFans creators ^[3].

Forgiveness follows the opposite pattern. Asked whether it can be reasonable to take back a partner who has cheated, 47% of over-60s said yes in some circumstances, compared with 22% of under-30s ^[3]. Overall, 37% thought it could be reasonable and 41% said never ^[3].

On sex before marriage, the age gradient runs the other way. In BSA 2022, 89% of 18 to 24 year olds saw nothing wrong in premarital sex, against 64% of those aged 70 and over ^[1]. Younger Britons are, on these figures, more relaxed about sex before commitment and stricter about behaviour once they are in a relationship, which fits the Natsal-3 finding that disapproval of non-exclusivity rose among under-45s ^[8].

What counts as cheating in Britain?

Almost everyone agrees that sex with someone else is cheating, and agreement falls away quickly after that. In YouGov's 2026 survey, 94% put sex with another person in that category, 82% sending nudes, 80% using dating apps and 73% kissing someone else ^[3]. Secretly messaging or meeting an ex counted for 69%, a deep emotional attachment for 52% and unacted romantic feelings for 40% ^[3].

Newer behaviours split opinion. Engaging with OnlyFans creators was called cheating by 47%, and sexting with AI chatbots by 30%, with women far more likely than men to count both (57% against 37% for OnlyFans, 38% against 22% for chatbots) ^[3]. Flirting counted for 26% and fantasising for 16% ^[3]. At the mild end, 29% called having a crush harmless and only 15% called it cheating, and the same 29% saw fantasising about someone else as harmless ^[3].

The 2010 poll asked a shorter list. Then, between 83% and 92% counted regular sex, a one-night stand or sex with a prostitute as cheating, while 45% of men and 59% of women counted kissing ^[4]. The wording and answer options changed between the two surveys, so the rise in the kissing figure to 73% in 2026 should be read with care ^[4][3].

Why are dating-site surveys unreliable?

Figures published by websites for people seeking affairs are marketing material, and they should not be read as measurements. A typical example came from Illicit Encounters, which describes itself as a dating site for married people: its "2021 infidelity index", reported in the run-up to Christmas, claimed that 168,322 people in London were having affairs, with estimates down to individual boroughs such as Newham (15,846) and Tower Hamlets (13,659) ^[11]. The local newspaper that reported the figures noted that they were grouped by postcode, which could inflate some areas, and the article said only that the estimates combined the site's own statistics, behavioural surveys and demographic research, with no further detail ^[11].

Such figures have several weaknesses. The sample is drawn from a site's own members or visitors, who are by definition people interested in affairs. The company has a commercial interest in showing that infidelity is common and rising; the same index attributed a rise in east London to unhappy partners seeking affairs once pandemic restrictions eased, a claim the newspaper presented as the company's own ^[11]. And full methods are rarely published, so the numbers cannot be checked.

Polls by established firms have their own limits. The YouGov figures are online panel surveys, often commissioned by newspapers, and the published articles do not always give question wording or sample sizes ^[4][5]. In the American YouGov poll of 2015, 7% preferred not to answer, and definitions of cheating differed by gender, so the headline rate depends on how the question was framed ^[6]. Natsal, with its random probability sample and confidential self-completion, sits at the other end of the scale, but it measures partners and attitudes and does not ask about cheating directly.

What did divorce petitions reveal about adultery before 2022?

Divorce petitions in England and Wales gave a running count of adultery claims until April 2022, but they measured legal strategy more than behaviour. Under section 1(2)(a) of the Matrimonial Causes Act 1973, a petitioner could prove breakdown by showing that the respondent "has committed adultery" and that the petitioner found it intolerable to live with them ^[12]. Adultery was one of five facts, alongside unreasonable behaviour, desertion and two separation periods, until the Divorce, Dissolution and Separation Act 2020 replaced the system on 6 April 2022 with a statement of irretrievable breakdown ^[12].

Adultery was never the most common fact overall. The Finding Fault study, led by Liz Trinder of the University of Exeter and published by the Nuffield Foundation in 2017, found that in 2015, 12% of divorces in England and Wales relied on adultery and 48% on behaviour ^[13]. In Scotland, only 6% of divorces were granted on adultery or behaviour ^[13]. The authors noted that fault was used in Scotland and France at about a tenth of the English and Welsh level, and that only about 2% of petitions were defended ^[13]. ONS bulletins show that adultery was generally the most common fact among husbands petitioning in the 1980s and 1990s, while wives have relied mainly on unreasonable behaviour since the late 1970s ^[14].

The legal definition was narrow. Adultery in this sense required sex with a person of the opposite sex, so it was not available to same-sex couples, whose divorces mostly relied on unreasonable behaviour ^[14]. In 2021, unreasonable behaviour was cited in 48.1% of opposite-sex divorces petitioned by women and 34.8% of those petitioned by men; among men it was level with two years' separation, which had become their most common fact in 2020 ^[15]. In 2019, ONS noted that unreasonable behaviour "includes adultery" in that wider sense, and it was the ground for 65% of same-sex divorces ^[16].

The petitions were also a poor guide to what had happened. In the Finding Fault survey, only 29% of respondents to a fault-based divorce said the fact used matched the real reason for the separation very closely, and the authors described petitions as a narrative produced to secure a divorce ^[13]. The report also observed that adultery "can be falsely claimed and admitted" ^[13]. Since 2022, the question is no longer asked: of the 80,057 divorces in 2022, 7,394 were under the new law, which requires no fact at all ^[17]. In 2021, the last full year of the old rules, England and Wales recorded 113,505 divorces ^[15]. The legal history is set out in from adultery grounds to no-fault divorce.

What will Natsal-4 add?

Natsal-4 is the next large source, and its first results are due at the end of November 2026 ^[18]. Its fieldwork ran from September 2022 to April 2024 and covered about 19,000 people aged 16 to 59, recruited through a mix of sampling and data collection methods ^[18]. The datasets are due to be archived under secure access at the UK Data Archive in early 2027 ^[18].

The age range is narrower than last time. Natsal-3 interviewed people up to 74 ^[8], while Natsal-4 stops at 59 ^[18], so its headline figures will not be directly comparable for older adults, the group YouGov found most forgiving of a partner who cheats ^[3].

Until those results appear, the most recent published probability-sample data on partnerships in Britain date from 2010 to 2012 ^[8], and Natsal-4 began its fieldwork a decade after Natsal-3 ended. Over that period, the YouGov list of behaviours people might count as cheating has grown to include dating apps, OnlyFans and AI chatbots, none of which appeared in the 2010 version ^[3][4]. Whether Natsal-4 publishes a concurrency measure, and how it defines it, will decide how far its figures can be compared with the 15% and 9% reported for men and women in 2000 ^[7].

Frequently asked questions

What percentage of people in the UK have cheated?

About a fifth to a quarter, according to YouGov. Its July 2026 poll found 23% of Britons who had been in a relationship said they had cheated, 17% sexually; polls in 2010 and 2015 gave 19% and 20%. These are self-reported figures from online panels.

Do men cheat more than women in Britain?

Slightly, in most surveys. YouGov in 2015 found 20% of men and 19% of women had had an affair, but men were more likely to have done so more than once. Natsal-2 found 15% of men and 9% of women with overlapping partners in the past year.

Is adultery seen as worse than sex before marriage in Britain?

Yes, by a wide margin. In British Social Attitudes 2022, 57% said extramarital sex is always wrong, while 78% saw nothing wrong at all in sex before marriage. The adultery figure has hardly changed since 1983.

What does Natsal say about infidelity?

Natsal does not ask directly about cheating. It measures partner numbers, overlapping partnerships and attitudes: in Natsal-3, 57.2% of men and 65.0% of women said sex outside a marriage or cohabitation is always wrong. Natsal-4 results are due at the end of November 2026.

Are infidelity statistics from dating sites reliable?

No. They come from companies selling affair services, draw on their own users and rarely publish methods. A widely reported Illicit Encounters index, for example, estimated affairs by London borough without publishing a detailed method.

How many UK divorces were for adultery?

About one in eight before the 2022 reform. The Nuffield Foundation's Finding Fault study found that 12% of divorces in England and Wales in 2015 relied on adultery, against 48% on behaviour. Since 6 April 2022, no fact has to be proved.

Do younger Britons think flirting is cheating?

More than older people do. In YouGov's 2026 survey, 45% of under-30s called flirting cheating, against 26% of all adults. Under-30s were also the least willing to take back a partner who had cheated.

When will Natsal-4 results be published?

At the end of November 2026, according to the Natsal team. The survey interviewed about 19,000 people aged 16 to 59 between September 2022 and April 2024. The data are due at the UK Data Archive in early 2027.